Systems of the above-mentioned type allow an operation to be followed not only by the principal observer or lead surgeon, but also by an assistant. A known system is marketed, for example, by the Applicant under the designation “M841 EBS.” In this known model, the zero-degree assistant's device is implemented as an insert that is inserted between the microscope body and the binocular tube for the principal observer. The zero-degree assistant's insert deflects a portion of the beam path into a corresponding assistant's tube, the beam paths in the assistant's tube and in the principal observer's tube being at a 90-degree angle to one another. With this known system, the microscope body contains the zoom systems as well as an illumination module for illuminating the object plane. In the known model, instead of the zero-degree assistant's insert it is also possible to use a “double-wing” insert that permits observation by two assistants standing opposite one another.
An examination is often documented as it proceeds. Provided for this purpose in the known model is a documentation module that can be inserted between the zero-degree assistant's insert and the binocular tube for the assistant. This documentation module in turn couples a portion of the beam path out and conveys it to specific image sensors. The image acquisition spectrum in this context ranges from conventional 35-mm photography to integrated 2D and 3D video systems.
The zero-degree assistant's insert is connected, via dovetail connections or other suitable connecting mechanisms, to the microscope body on the one side and to the binocular tube for the principal observer on the other. The documentation module is in turn connected, using corresponding connecting mechanisms, to the binocular tube for the assistant. During an examination or a procedure it is often necessary to change the position of the assistant. At present this can be done only by disassembling the corresponding modules or inserts, rotating the zero-degree assistant's insert 180 degrees (from left to right or right to left), and realigning and reinstalling the inserts or modules.
In the context of the surgical microscopes mentioned at the outset, it is extremely impractical, complex, time-consuming, and—not least—dangerous to disassemble, reorient, and reinstall the documentation module (if present) together with its documentation accessories, as well as the principal observer's tube and any laser filters, etc. that may be present, whenever the assistant changes sides, especially if the assistant needs to change sides during an operation. Lastly, the risk exists that the parts being disassembled and installed may collide or be dropped.
U.S. Pat. No. 5,898,518 discloses a stereomicroscope having an assistant's insert and a separate illumination module, the illumination module and the assistant's insert being able to assume at least two different positions by rotation about an axis. The construction of this microscope is such that the distance between the assistant's tube and the principal observer's tube must in any case always be sufficient to ensure collision-free rotation of the assistant's tube. The result of this, however, is that the microscope's overall height is undesirably high.